Catalytic conversion of hydrocarbons



ug 4, 1942- G. EGLoFF CATALYTIC CONVERSION OF HYDRCARBONS FilediAug. 21, 1940 uw@ v w u. n

NN NN Ill . desulfurization occurs.v

Patented AAug. 4,' 1942 OFFICE oA'rALY'rIo CONVERSION oF Himno- ARBO Gustav Egloi, Chicago, Ill., assignor to 'Universal f' il Products Company,

ration of Delaware Chicago, Ill., a. corpos Application August 21, 1940, Serial No. 353,517

(oi. 19e-,53) l Claims.

This invention relates to a process for converting hydrocarbon oil into substantial yields of high anti-knock gasoline. More particularly it relates to a combination catalytic cracking and reforming process wherein gasoline of desirable properties is produced from hydrocarbon distillates containing substantial quantities of sulfur lyst, separating the reaction products into gas,v` gasoline and a distillate fraction, removing the hydrogen sulde from the gas as hereinafter indicated, subjecting the'gasoline toa catalytic reforming step in the presence of powdered catalyst, subjecting thedistillate fraction of charging stock to catalytic cracking in thevpresence of a powdered catalyst, recovering gasoline and gas, combining the gas with the gas from the aforesaid desulfurizing step, removing sulfur therefrom,'supplying a portion of hydrogen-containing gasto the said desulfurizing step and returning a portion of the higher boiling oil from the catalytic cracking step to the desuliurizing step.

The process is further understood by reference to the accompanying drawing whichis diagrammatic and ,should not be lconstrued as limiting it to the exact apparatus shown therein.

'Ihe charging stock for the process is intro-v generated in the process. The reaction mixture maybe heated to a temperature within the range of approximately 30G-800v F. and preferably 30D-600 F. at a pressure of approximately 100-1000 pounds per square inch or higher in coil 4.v The mixture then passes through line `II and ,valve I2 -to reactor I3 wherein further The reaction products pass through line I4 and valve I5 tofractionator compounds. Such distillates may be from any I6. A portion of the catalytic agent and higher boiling oil may be withdrawn from the fractionator through line I1 and valve I8 While another portion'may be recycled to the dehydrogenation step through line I9 containing valvel 20 and pump 2I', joining with line I. Gas is removed through line 22, valve 23, pump 24, valve 25 and line 26 to separation step 21 which is illustrated diagrammatically and wherein the process -gases are subjected to desulfurization wherein hydrogen sulfide is removed substantially completely. This-step may consist of a series of separating and treating vessels wherein the desulfurization and separation of a portion of the hydrocarbon hydrocarbons may beremoved and recoveredv for further catalytic treatment toproduce gasoline. The removal of hydrogen sulfide may` be accomplished by any well-known method, such as treatment with alkali metal hydroxides or carbonatos, or by treatment with tripotassium phosphate or alkyl hydroxylamines and thelike. A portion of the hydrogen-containing gas is passed from desulfurizing step 21 through line 28, valve 29, pump 30, line 3|, valve 32, line 33.and valve 34. to line I and thus returned to the system.

A portion of the gases may be ,removed from the system through line 35 and valve 36. The gases may be enriched by the addition of hydrogen through line 31 and valve 38. 'I'he gasoline fraction or a fraction boiling substantially within the gasoline range is removed'through line 39, valve 48 and pump 4I, and is mixed withhydrogen-containing gas from separation. step 21, entering through line 42 and valve 43. The mixture passes through line 44 and valve 45 to coil 46 which is disposed in heater 41. It is mixed with a suitable reforming catalyst from catalyst charger 48, passing throughline 49, valve 50, pump 5I and valve 52. This catalyst may consist of a relatively inert support such as alumina,

magnesla, bauxite, silica, diatomaceous earth,

zinc oxide, titania and the like, having depositedl thereon a promoting compound or compounds and particularly an oxide of a metal appearing in the left-hand column of'groups I V, V and VI of the periodic table. lParticularly suitable for this purpose are the oxides vof chromium,V I molybdenum, vanadium, and tungsten. 'I'hese catalytic agents are not necessarily equivalent in their action and the process is not :intended t'o be limited to the parucmar catalyst described.'

The reaction mixture passes through.line 53 and valve 54 yto reactor `55, being maintained at 55. a temperature' within the range of approximately 900-1200 F. and pressures preferably atmospheric or slightly superatmospheric, of the order oi.' 50-100 pounds per square inch, although somewhat higher pressures may also be used. The mixture passes through line 56 and valve 51 to fractionator 58. Gasoline and gas are removed through line 59 containing valve 60, condenser 6| and valve 62, being'collected in receiver 63 from which gasoline is recovered through line 64 and valve 65. The gasoline may be subjected to such subsequent stabilization and additional treatment as may be necessary to produce a finished product.

'I'he receiver gases pass through line 66 containing valve 61, pump 68 and valve 69 to line 26 and thence to desulfurizer 21. Material boiling above the gasoline range is removed through line 10 and valve 1|. The spent catalyst may be recovered therefrom and reactivated by heating with an oxygen-containing gaswhereby carbonaceous deposits are removed therefrom and catalytic activity is restored.

Returning to fractionator I6, a distillate fraction of the desulfurized charging stock which may boil within the kerosene,gas oil or wax distillate boiling range, is removed through line 12 containing valve 13, pump 14 and valve 15. This is mixed with the powdered cracking catalyst from catalyst charger 16 entering through line 11 containing valve 18, pump 19 and valve 80. The mixture enters coil 8| which is disposed in heater 82 and is heated under catalytic cracking conditions of temperature and pressure, usually within the range of 500-1200 F. and substantially atmospheric to 1000 pounds per square inch pressure. The temperatures ordinarily employed are within the range of approximately 8001100 F. and pressures below approximately 100 pounds per square inch.

'Ihe reaction mixture passes through line 83 and valve 84 to chamber 85. Spent catalyst and residual oil may be withdrawn' through line 86 and valve 81, the catalyst being recovered and subjected to \reactivating treatment preferably in the presence of an oxygen-containing gas whereby the catalytic activity is restored. A

`vaporous portion of reactants pass through line 88 and valve 89 to fractionator 90. Gasoline and gas are removed through line 9|, valve 92, condenser 93 and valve 94uto receiver 95 from which gasoline is removed through line 96 and valve 91 to suitable stabilizing equipment not shown. The receiver gases pass through line 98, valve 99, pump |00, valve to line 26 and desulfurizing step 21. An intermediate fraction of insufficiently converted oil from fractionator |v may be 'recycled through line |02, valve |03, pump |04 and valve |05 to line 12 and thus to coil 8|. The higherboiling fraction may be withdrawn in part through line |06 and valve |01. A portion or all of of theoil may be passed through line |08, valve |09, pump ||0 and valve to line I9 and thus supplied to coil 4 of the primary desulfurizing step.

The catalyst used in the catalytic cracking step may consist of a composite of precipitated silica may also'be added. The composite is prepared desirable properties and containing.substantiallyl no sulfur. This is accomplished under conditions such that the losses in volume, antiknock propertiesV` and other desirable properties of the gasoline, resulting from treatment lof cracked or reformed gasoline in the usual manner, are substantially eliminated. By this method of treatment `it is pome to produce a substantially sulfur-free product. Both the catalytic cracking and reforming steps have a tendency to produce gasoline of low sulfur content, but the sulfur is not completely eliminated. By giving the charging stock a preliminary treatment whereby a major portion of the Asulfur contained therein iskreinoved, the relatively minor amounts of sulfur left in the charge to the reforming and cracking steps are readily taken care of in these processes and the result is a gasoline containing little or no sulfur. The importance of removing sulfur substantially completely has been recently emphasized, particularly in regard to ther antiknock properties ofthe gasoline when tetraethyl lead is added thereto to improve the octane number. increased yields of gasoline per pass are obtainable from charging `stock which has been treated in this manner due to the removal in the hydroge'nating step of impurities which tend to decrease the catalytic activity of the catalysts used in the subsequent steps. y

It should be borne in mind that the hydrogenating step is intended to be operated under conditionssuch that little or no destructive hydrogenation occurs; that is, there is little or no conversion of the higher boiling hydrocarbons into the gasoline range.

The following example is given to illustrate the usefulness and practicability of the process but should not be construed as limiting it to the exact conditions given therein. i

A fraction of hydrocarbon oil obtained by Vthe distillation of crude oil to remove a fraction boiling from approximately 20G-760 F. was mixed with approximately 2% by weight of a catalyst comlprising molybdenum `oxide deposited on alumina.

This ixture may be treated at 1000 pounds per square inch and 700 F. in the presence of a hydrogen-containing gas and then separated into gas,` gasoline, intermediate boiling fraction and residue. The gas may be desulfurized as described by treatment with tripotassium phosphate and a portion thereof returned to process.

A portion of residual oil containing partially l spentcatalyst in suspension may also be reby the separate or simultaneous precipitation of A cycled while the major portion of the catalyst and higher boiling oil is withdrawn from the system. The catalyst is recovered and separately regenerated. A naphtha fraction boiling up to approximately 425 1".r may be mixed with a portion of the desulfurized gases and subjected to catalytic reforming in the presence of a powdered catalyst comprising a major portion of The process has the advantage thatA activated alumina having deposited thereon a minor portion of an oxide of chromium. Y The temperatures employd are of the order of 575 F. at substantially atmospheric pressure. A re- `formed gasoline having an antikock value of 80 may be recovered. The sulfur content of this material is less than 0.001%. Receiver gases are subjected to a desulfurizing treatment to remove hydrogen sulde. A fraction including kerosene and gas oil from the original desulfurization step may be catalytically cracked in the presence of a silica-alumina powdered cracking catalyst at a temperature of 1000 F. and substantially atmospheric pressure. Gasoline having an antiknock value of 79 may be rec/overed.

The gases are sent to the gas desulfurizing step.

mally gaseous products prior to the hydroge sulde removal step.

2. The process of claim 1 further characterized in that desulfurizing and reforming are accomplished in the presence of a comminuted cat-alyst suspended in the charge to each step.

3. The process of claim 1-further characterized i in that a relatively heavy oil is separated' from A portion of the insufficiently converted oil may l be returned tothe primary desulfurizing step. The gasoline from the cracking step may have a sulfur content of approximately that of the reformed gasoline. When using 3 cc. of tetraethyl lead per gallon of gasoline, the increase in octane number obtainable from gasoline of the present process is approximately two numbers greater than that obtainable when a naphtha is reformed and the kerosene-gas oilfraction is cracked without the preliminary treatment.

I claim as my invention:

1. A process for the conversion of hydrocarbon oil, which comprises subjecting said oil to desulfurizing conditions in the presence of a desulfurizing catalyst and hydrogen whereby to form hydrogen sulde from sulfur compounds and form a substantallysulfur-free oil, separating from the products of desulfurization a fraction comprising normally gaseous products including hydrogen and hydrogen sulfide and a gasoline fraction, treating the lrst mentioned fraction to remove-hydrogen sulde, returning at least a portion of the substantially hydrogen sulde free gases to the desulfurization step, combining another portion of the substantially hydrogen sulfide free gases with said gasoline fraction and subjecting the mixture to reforming conditions in the presence of a dehydrogenating catalyst, to reform the gasoline and to form additional hydrogen, separating a hydrogen fraction including, said additional hydrogen from the reformed gasoline, recovering the latter, and combining said hydrogen fraction with the northe products of desulfurization and returned to the desulfurization step for further treatment.

4. A process for the conversion of hydrocarbon oil, which comprises subjecting said oil to desulfurizing conditionsin the presence of a desulfurizing catalyst and hydrogen whereby to form hydrogen sulfide from sulfur compounds and form a substantially sulfur-free oil, separating fromv the products of desulfurzation a fraction comprisingnormally gaseous products including hydrogen and hydrogen sulde, a gasoline fraction, a gas oil fraction and a fraction heavier than gas oil, returning the last mentioned fraction to the desulfurizing step, treating the rst mentioned fraction to remove hydrogen sulfide, returning a, portion of the hydrogen sulfide free gases to the desulfurizing step, combining another portion of the substantially hydrogen sulde free gases with said gasoline and subjecting the mixture to reforming conditions in the presence of a dehydrogenating catalyst to re- Y step, subjecting said gas oil fraction to cracking conditions in the presence of a cracking catalyst,

fractionating conversion products of the last reflux condensate and aheavier reflux condensate, the latter returned to the desulfurizing step and the former returned to the cracking step.

GUSTAV EGLOFFK 

